scholarly journals Gas-Phase and Computational Study of Identical Nickel- and Palladium-Mediated Organic Transformations Where Mechanisms Proceeding via MII or MIV Oxidation States Are Determined by Ancillary Ligands

2015 ◽  
Vol 137 (42) ◽  
pp. 13588-13593 ◽  
Author(s):  
Krista L. Vikse ◽  
George N. Khairallah ◽  
Alireza Ariafard ◽  
Allan J. Canty ◽  
Richard A. J. O’Hair
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Oxidation States ◽  
Organic Transformations ◽  
Ancillary Ligands

Explaining the magnetism of gold

2017 ◽  
Author(s):  
Robson de Farias
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Formation Enthalpy ◽  
Gold Atom ◽  
Orbital Energy ◽  
Knudsen Effusion ◽  
Energy Diagram ◽  
Unpaired Electrons ◽  
The Difference ◽  
Good Agreement

<p>In the present work, a computational study is performed in order to clarify the possible magnetic nature of gold. For such purpose, gas phase Au<sub>2</sub> (zero charge) is modelled, in order to calculate its gas phase formation enthalpy. The calculated values were compared with the experimental value obtained by means of Knudsen effusion mass spectrometric studies [5]. Based on the obtained formation enthalpy values for Au<sub>2</sub>, the compound with two unpaired electrons is the most probable one. The calculated ionization energy of modelled Au<sub>2</sub> with two unpaired electrons is 8.94 eV and with zero unpaired electrons, 11.42 eV. The difference (11.42-8.94 = 2.48 eV = 239.29 kJmol<sup>-1</sup>), is in very good agreement with the experimental value of 226.2 ± 0.5 kJmol<sup>-1</sup> to the Au-Au bond<sup>7</sup>. So, as expected, in the specie with none unpaired electrons, the two 6s<sup>1</sup> (one of each gold atom) are paired, forming a chemical bond with bond order 1. On the other hand, in Au<sub>2</sub> with two unpaired electrons, the s-d hybridization prevails, because the relativistic contributions. A molecular orbital energy diagram for gas phase Au<sub>2</sub> is proposed, explaining its paramagnetism (and, by extension, the paramagnetism of gold clusters and nanoparticles).</p>

2-Deoxyribose Radicals in the Gas Phase and Aqueous Solution. Transient Intermediates of Hydrogen Atom Abstraction from 2-Deoxyribofuranose

2005 ◽  
Vol 70 (11) ◽  
pp. 1769-1786 ◽  
Author(s):  
Luc A. Vannier ◽  
Chunxiang Yao ◽  
František Tureček
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Atom ◽  
Gas Phase ◽  
Computational Study ◽  
Hydrogen Atom Abstraction ◽  
Oh Radical ◽  
Free Energies ◽  
Intramolecular Hydrogen ◽  
Solvation Free Energies ◽  
Transient Intermediates

A computational study at correlated levels of theory is reported to address the structures and energetics of transient radicals produced by hydrogen atom abstraction from C-1, C-2, C-3, C-4, C-5, O-1, O-3, and O-5 positions in 2-deoxyribofuranose in the gas phase and in aqueous solution. In general, the carbon-centered radicals are found to be thermodynamically and kinetically more stable than the oxygen-centered ones. The most stable gas-phase radical, 2-deoxyribofuranos-5-yl (5), is produced by H-atom abstraction from C-5 and stabilized by an intramolecular hydrogen bond between the O-5 hydroxy group and O-1. The order of radical stabilities is altered in aqueous solution due to different solvation free energies. These prefer conformers that lack intramolecular hydrogen bonds and expose O-H bonds to the solvent. Carbon-centered deoxyribose radicals can undergo competitive dissociations by loss of H atoms, OH radical, or by ring cleavages that all require threshold dissociation or transition state energies >100 kJ mol-1. This points to largely non-specific dissociations of 2-deoxyribose radicals when produced by exothermic hydrogen atom abstraction from the saccharide molecule. Oxygen-centered 2-deoxyribose radicals show only marginal thermodynamic and kinetic stability and are expected to readily fragment upon formation.

A vibrational spectroscopic and computational study of the structures of protonated imidacloprid and its fragmentation products in the gas phase

2021 ◽  
Vol 23 (5) ◽  
pp. 3377-3388
Author(s):  
Kelsey J. Menard ◽  
Jonathan Martens ◽  
Travis D. Fridgen
Keyword(s):  
Computational Chemistry ◽  
Gas Phase ◽  
Vibrational Spectroscopy ◽  
Computational Study ◽  
Unimolecular Decomposition ◽  
Decomposition Products

Vibrational spectroscopy and computational chemistry studies were combined with the aim of elucidating the structures of protonated imidacloprid (pIMI), and its unimolecular decomposition products.

Ion chemistry of second-row transition metals in hydrocarbon flames: cations and anions of Y, Zr, Nb, and Mo

1995 ◽  
Vol 73 (12) ◽  
pp. 2263-2271 ◽  
Author(s):  
Christine C.Y. Chow ◽  
John M. Goodings
Keyword(s):  
Transition Metals ◽  
Gas Phase ◽  
Atmospheric Pressure ◽  
Chemical Ionization ◽  
Negative Ions ◽  
Ion Concentration ◽  
Oxidation States ◽  
Metallic Ions ◽  
Ion Chemistry ◽  
Hydrocarbon Flames

A pair of laminar, premixed, CH4–O2 flames above 2000 K at atmospheric pressure, one fuel-rich (FR) and the other fuel-lean (FL), were doped with ~10−6 mol fraction of the second-row transition metals Y, Zr, Nb, and Mo. Since these hydrocarbon flames contain natural ionization, metallic ions were produced in the flames by the chemical ionization (CI) of metallic neutral species, primarily by H3O+ and OH− as CI sources. Both positive and negative ions of the metals were observed as profiles of ion concentration versus distance along the flame axis by sampling the flames through a nozzle into a mass spectrometer. For yttrium, the observed ions include the YO+•nH2O (n = 0–3) series, and Y(OH)4−. With zirconium, they include the ZrO(OH)+•nH2O (n = 0–2) series, and ZrO(OH)3−. Those observed with niobium were the cations Nb(OH)3+ and Nb(OH)4+, and the single anion NbO2(OH)2−. For molybdenum, they include the cations MoO(OH)2+ and MoO(OH)3+, and the anions MoO3− and MoO3(OH)−. Not every ion was observed in each flame; the FL flame tended to favour the ions in higher oxidation states. Also, flame ions in higher oxidation states were emphasized for these second-row transition metals compared with their first-row counterparts. Some ions written as members of hydrate series may have structures different from those of simple hydrates; e.g., YO+•H2O = Y(OH)2+ and ZrO(OH)+•H2O = Zr(OH)3+, etc. The ion chemistry for the production of these ions by CI in flames is discussed in detail. Keywords: transition metals, ions, flame, gas phase, negative ions.

Computational study of the concerted gas-phase triple dissociations of 1,3,5-triazacyclohexane and its 1,3,5-trinitro derivative (RDX)

1991 ◽  
Vol 95 (20) ◽  
pp. 7699-7702 ◽  
Author(s):  
Dariush Habibollahzadeh ◽  
Michael Grodzicki ◽  
Jorge M. Seminario ◽  
Peter Politzer
Keyword(s):  
Gas Phase ◽  
Computational Study

A computational study on the gas phase reaction of Os+ with N2O

2009 ◽  
Vol 20 (8) ◽  
pp. 1010-1014 ◽  
Author(s):  
Tao Hong Li ◽  
Chuan Ming Wang ◽  
Shi Wen Yu ◽  
Xiang Yi Liu ◽  
Hui Fu ◽  
...  
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Phase Reaction ◽  
Gas Phase Reaction

Molecular Geometry of Vanadium Dichloride and Vanadium Trichloride: A Gas-Phase Electron Diffraction and Computational Study

2010 ◽  
Vol 49 (6) ◽  
pp. 2816-2821 ◽  
Author(s):  
Zoltán Varga ◽  
Brian Vest ◽  
Peter Schwerdtfeger ◽  
Magdolna Hargittai
Keyword(s):  
Electron Diffraction ◽  
Gas Phase ◽  
Computational Study ◽  
Molecular Geometry ◽  
Gas Phase Electron Diffraction

scholarly journals Crystal structure, computational study and Hirshfeld surface analysis of ethyl (2S,3R)-3-(3-amino-1H-1,2,4-triazol-1-yl)-2-hydroxy-3-phenylpropanoate

2019 ◽  
Vol 75 (12) ◽  
pp. 1919-1924
Author(s):  
Abdelkader Ben Ali ◽  
Youness El Bakri ◽  
Chin-Hung Lai ◽  
Jihad Sebhaoui ◽  
Lhoussaine El Ghayati ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Gas Phase ◽  
Surface Analysis ◽  
Computational Study ◽  
Hirshfeld Surface ◽  
Hirshfeld Surface Analysis ◽  
Dft Methods ◽  
Important Interaction ◽  
The Mean ◽  
Title Molecule

In the title molecule, C13H16N4O3, the mean planes of the phenyl and triazole rings are nearly perpendicular to one another as a result of the intramolecular C—H...O and C—H...π(ring) interactions. In the crystal, layers parallel to (101) are generated by O—H...N, N—H...O and N—H...N hydrogen bonds. The layers are connected by inversion-related pairs of C—H...O hydrogen bonds. The experimental molecular structure is close to the gas-phase geometry-optimized structure calculated by DFT methods. Hirshfeld surface analysis indicates that the most important interaction involving hydrogen in the title compound is the H...H contact. The contribution of the H...O, H...N, and H...H contacts are 13.6, 16.1, and 54.6%, respectively.

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